Non-invasive magnetopneumographic estimation of lung dust loads and distribution in bituminous coal workers.

Magnetopneumography is a non-invasive technique for measuring the ferrimagnetic portion of retained dust in the lungs by means of its permanent magnetism. Magnetopneumography was used to measure the magnetic fraction of coal mine dust in 21 retired disabled bituminous coal miners and 14 active miners. Twenty rural subjects served as controls. The retired disabled miners had significantly higher levels of pulmonary ferrimagnetic mineral than the control subjects and most active miners (p < 0.001). Three of the active miners had significantly higher levels of ferrimagnetic mineral than did the other active miners and the control subjects (p < 0.005), yet could not be differentiated from other miners by work history or chest roentgenograms. This elevation could not be accounted for by sources other than coal mine dust. A pattern of central hilar concentration of ferrimagnetic mineral was noted in both retired and active miners. These results suggest that magnetopneumography is sufficiently sensitive to permit the non-invasive study of coal mine dust accumulation and distribution in the lung.